Telegraphy



R PARKER TELEGRAPHY A ril 21, 1925' Filed May 1920 [m LEFQDZ K" POlWr it=f INVENTOR'.

. BY Raf AT O Patented Apr. 21, 1925.

UNITED STATES PATENT OFFICE.

RALZEMOND D. PARKER, OF BROOKLYN, NEW YORK, ASSIGNOR TO AMERICAN TELE- PHONE AND TELEPGRAPH COMPANY, A CORPORATION OF NEW YORK.

TELEGRAPHY.

Application filed May 20,

To all whom it may concern:

,Be it known that I, RALzEMoND D. PAR- KER, residin at Brooklyn, in the county of Kingsand tate of New York. have invent ed certain Improvements in Telegraphy, of which the following is a specification.

This invention relates to telegraphy, and it is concerned particularly with telegraph systems in which transmission is limited to one direction or the other at a time, which systems are generally designated in the art as single telegraph systems.

In the single telegraph systems now in common use the line relays are of the type which is responsive to the presence or absence of line current irrespective of the direction thereof. Systems of this character are troublesome, when used on long lines, due to leakage and capacity. In such instances it is not uncommon to' employ a duplex telegraph system modified for oneway operation, the advantage of this systenr being that it employs relays responsive to the direction of current, as for example, relays with polarized armatures. The duplex systems, however, necessitate the use of balancing artificial lines and other equipment which is expensive to install and troublesome to keep in adjustment.

The object of the present invention is to provide a single telegraph system which employs relays. of the type responsive to current reversals, thus securing the operating advantages of these relays for the single systems without the use of balancing artificial lines and similar equipment.

Various other features and objects of the invention will be readily understoodfrom the following description of specific forms of embodiment thereof, having reference to the accompanying drawing in which,

Figure 1 is a circuit diagram showing one form of embodiment of the inventions in simplified form, and v Fig. 2 isa similar diagram showing the apparatus at, a terminal station arranged to repeat signals from the main line to a branch loop and Vice versa.

Similar reference characters designate similar parts in each of the several views.

In Fig. 1 of the drawing I have shown polarized relays" LR and LR located atsta-f tions A and B, the-relays being connected with each other by means of aline conductor. Keys K and K are associated 1920. Serial No. 382,852.

that the polarized relays hold their contacts in their closed positions. The sounders, whose circuitsare controlled by these contacts, are therefore normally energized. The batteries (Z and (Z, of higher potential than c and 0, are associated with the back contacts of the keys, the polarity of the back contact battery of each key being opposed to that of the front contact battery of the same key, so that when either key is opened the line circuit current is reversed in direction. The value of the reversed current should preferably be substantially equal to that of the normal current, and since the latter is proportional to the potential of batteries 0 and 0 in conjunction,

whereas the former is proportional to that of (Z and c or (Z and 0, in opposition, it follows that the potential of the d batteries should be substantially three times that of the 0 batteries.

The operation of the system will now be readily understood. To send a message to station B, the operator at A opens his key so that battery (Z causes a reversal of current in the line circuit and the de-energization of the sounder; at both stations. He then sends the message in the regular mannerxby operating his key, a dot or dash being made by the closure of the front contact of the key and a space bv the closure of the back contact thereof. Transmission from B to A is similar.

To break a message the receiving operator, as B, opens his key so that the back contact battery is associated with the line. If the key at A is closed at this instant, so as to send a marking signal to B, the current in v p the line is reversed by the battery d and the then in conjunction. The operator at' A is thus notified by failure of res on'se of the sounder to the operations of t e key, that the operator at B is breaking hls message.

He then closes his key and receives the message from B. I

In Fig. 2 I have shown the system of my invention arranged to cause the repetition 5 of a message from a main line circuit into a branch loop, and vice versa. The apparatus is shown only for one terminal station, namely A, it being understood that the other station associated with the. line is preferably provided with similar apparatus. The transmitting key K of Fig. 1 is replaced in this system by a transmitting relay D, the circuit of which is governed by keys K, and K which are: comprised in a loop circuit extending to a branch ofiiceor subscriber. Operation of relay D may therefore be efi'ected by the actuation of either key K,, which may be at e the main station, of key -K which may be at the branch oflice. The relay D closes'its front contact in response to a dot or dash and its back contact in response to a space. Batteries 0 and (Z are associated ith the contacts of D and serve to cause reversals of current in the line circuit, similarly as in the preceding embodiment. The polarized rela'y LR governs a sounder which is connected in series with the winding 1 of a, relay B.- This relay governs the contact 6 which is in series .with the loop circuit hereinbefore mentioned and which comprises a sounder atv the branch ofiice. Relay B serves, therefore, to open and close contact 6 in response to the operation of relay LR, thus bringing about the repetition of a message from the main line circuit into the loop circuit. 5

Since relay LR, however, responds not only to incoming signals but also to out going ones it is necessary to prevent the response of relayB to the outgoing signals so that relay .D and the loop circu-itmay re main under the control of key K or K,.. This is accomplished by the provision of a locking,winding'2-onrelay B, which winding is'energized by current from battery 3, provided a shunt for this winding is open at front contact 430i relay D.. The locking winding of relay "B is therefore energized when relay D is opened by keys K or K 0 and serves thus to pre cut an opening of the (local circuit at the con act of relay B when the relay LR reverses itscontact due to an outgoing signal.

eans are' provided also for preventing the operation oi the relay D due to the opening and closing of the 'loop circuit caused by the repeating relay B. This means comprising;- the locking winding 11 of relay D, which winding is energized by current from the battery 12, except when the relay B closes its front contact 13, which serves, when closed, to shunt current from thewindingll. Consequently when relay B opens contact 6 in response to an incommg spacing signal, and causes this the deenergization of the winding 10 of relay D, winding 11 prevents the opening of the cont-act of the relay because current now flows through this winding due to the opening of contact 13 of relay B. This arrangement, therefore, serves to prevent the repetition of an incoming message back into the line. The manner in which signals may be transmitted or received by the above-de-. scribed apparatus will be apparent without further description.

, Although only certain specific forms of apparatus and circuits embodying the invention are shown and described herein, it is readily understood that various changes and modifications may be made therein within the scope ofthe following claims without departing from the spirit and scope of the invention. r

What I claim is: a

1. In a telegraph system, a line, a plurality of relays associated with the opposite ends thereof and responsive to reversals of current therein, transmitting devices associated with said relays, a source of current associated with each device, said sources being arranged to be in aiding relation in a predetermined like position of said devices, and another unequal source of current of opposite polarity associated with each de' vice and arranged to be in opposition to the first mentioned source at the distant end in front and back contacts, batteries associate with the front contacts of said devices and arranged to be in conjunction when the said contacts are closed, a second batte for each device associated with the bee contact thereof, the said second battery of each device being arranged to oppose the front contact battery of the other device and the relative potentials of said batteries being such that the flow of current in each direction is substantially equal when the first contact or one device is held closed and the contacts of the other device are alternately closed and opened. 1

-3. In a single telegraph system, a line, a plurality of polarized relays responsive to reversals ofcurrent therein, sources of current and operating means adjacent each end of theline for causing reversals of'current therein, and a relay adjacent each end of the line for at times preventing reversals of current in the line in response to actuations of said operating means.-

4. In a single telegraph system, a plurality of polarized relays, a line for operatively associating the same, unequal batiao teries adjacent each end of the line and a key to associate said batteries alternatively for causing reversals of magneto-motive force in the relay of the opposite end, said relay being located between said line and said means.

5. In a single telegraph system, two polarized relays, a line for associating the same, operating means adjacent each relay for causing responses of both said relays, two other relays controlled respectively by the said polarized relays and respective sounders controlled by these said other relays and means adjacent each polarized relay for rendering the sounder at that end of the line non-responsive to the operating means adjacent thereto.

6. In a, single telegraph system, a line circuit, a plurality of polarized relays asgociated with the terminals thereof, two transmitting devices at each end of the line,

, one adjacent and the other non-adjacent for causing said relays to assume certain predetermined positions in response to actuation of either of said transmitting devices, and means operable at either transmitting device for rendering the non-adjacent device inefi'ective to cause the relay adjacent thereto to assume its pre-determined position.

7. In a telegraph system,a plurality of stations, a line circuit extending therebetween, polarized relays associated with said circuit, sources of current at said stations, having positive and negative potentials, and transmitting devices associated therewith for connecting said sources in aiding relation for one signal and in opposition for another signal.

8. In a telegraph system, a line, two polarized relays in said line, and two opposite alternative grounded batteries of difierent strength at each end of the line with a corresponding key to make connection to one or the other of them, the batteries of like strength being connected in conjunction for like positions of said keys.

In testimony whereof, I have signed my name to this specification this 19th day of May 1920.

RALZEMOND D. PARKER. 

